1. Technical Field
The present invention relates to image processing methods, storage media storing programs and image processing apparatuses.
2. Related Art
If dust is attached to an original, the images of such dust are included in the digital image of the original read by a scanner. For this reason, it is preferable to remove dust on an original with a blower or the like before the original is read. However, it is difficult to completely remove dust from the original.
Therefore, means is proposed for detecting dust images in a digital image to remove the same (see British Patent Publication No. 1547811, specification, JP-A-2003-101732 and JP-A-10-232915).
British Patent Publication No. 1547811, specification, discloses an apparatus for detecting dust on the original using infrared light. However, since provision of hardware such as an infrared light source is required, the apparatus becomes expensive.
JP-A-2003-101732 discloses a technique in which a binary image is subjected to a labeling process so as to enclose an individual image block with a rectangular frame. The image block enclosed with such a rectangular frame that falls under predetermined conditions is judged to be a dust image component. However, since a generation process of the binary images is not clear, it is not certain whether this technique is applicable to any type of image.
Further, as a method for removing a defective image (including a dust image, noise and the like) such as a dust image, there is known a process of moving averages, a median filtering process and the like. However, in the process of moving averages, there is a possibility that the image becomes blurred, and the image quality may deteriorate. Further, the median filtering process is suited for removing a random noise, but if the defective image is large, there is a possibility that the defective pixel will be replaced by a defective pixel.